控制阀的气蚀
Fisher 抗气蚀阀内件适用于控制阀，可在清洁和脏污工况中消除或控制气蚀损耗。
Fisher 抗气蚀阀内件适用于控制阀，可在清洁和脏污工况中消除或控制气蚀损耗。
气蚀是由压力和速度变化引起的液体流路内蒸气泡（空心）的形成和分解。控制阀内非受控气蚀有四种主要负面影响：噪音大、振动过度、材料损耗以及流动效率低。阀内件的有形损耗通常表现为外观凹痕且粗糙。
控制阀气蚀仅在液体流动时出现，气体不产生气蚀。
当液体通过控制阀时，如果液体压力降至气相压力，会产生蒸气泡。这些气泡沿着管道向下，由于压力增加，气泡会突然破裂或内爆，从而产生气蚀。
气蚀是流体堵塞所产生的一种结果。可以保持恒定的入口压力的同时增加压降，而不增加流速，这个位置称为堵塞点。
气蚀损耗的特点是，表面腐蚀后表面呈圆形煤渣状。在蒸汽转换为液体状态时，高速破坏性喷射和局部振动波会腐蚀控制阀材料表面。
不是每一次发生气蚀都会产生损耗。
气蚀损耗程度受多种因素影响：
气蚀会引起不可接受的噪音和振动。通常被描述为控制阀内好像有碎石块滚动。
虽然气蚀性液体产生的噪音很大，但我们更担心由此引起的材料损耗。
而气蚀造成的振动比损耗更加普遍。它可能影响阀门定位器、连杆、管道以及相邻管道。
损耗性气蚀在不产生噪音时也可能会出现，且控制阀的噪音和振动级别也不可能时刻与气蚀损耗级别一致。
可采用多种方式处理控制阀气蚀。第一种方式是通过控制压降，消除气蚀及其损耗。如图所示，通过使用多阶内件将整个控制阀的压降分割为小部分，从而消除气蚀。
第二种方式不能消除气蚀，但可以降低或隔绝损耗。其目的是隔绝控制阀表面气蚀，且受气蚀影响的表面将变硬。
第三种方式是通过某种方式改良系统，阻隔气蚀产生的根源。
艾默生工程师对气蚀应用进行噪音和振动测试。透明管道使气蚀位置可视。如需进行气蚀演示，请联系当地艾默生销售办事处。
Come along as we demonstrate the Fisher™ Cavitrol™ Hex Trim, which provides improved performance for severe service applications and maintains the efficiency of a rotary valve.
This video shows the damaging effects of cavitation on a control valve and downstream piping. Then it shows the difference that Fisher Cav Hex trim has on eliminating the effects of cavitation.
Learn more about valve cavitation and some of the technical solutions using Fisher products.
Get a unique look at the effects of cavitation in a pipeline, including turbulent flow and noise, and learn how you can reduce your risk with Fisher solutions.
See the difference valve trim can have on pipeline flow patterns in this side-by-side setup at the Emerson Innovation Center for Fisher technology.
Learn more about reducing flow pressure in stages to avoid the damaging effects of cavitation from sudden pressure drops.
Come along as we demonstrate the Fisher™ Cavitrol™ Hex Trim, which provides improved performance for severe service applications and maintains the efficiency of a rotary valve.
This video shows the damaging effects of cavitation on a control valve and downstream piping. Then it shows the difference that Fisher Cav Hex trim has on eliminating the effects of cavitation.
Learn more about valve cavitation and some of the technical solutions using Fisher products.
Get a unique look at the effects of cavitation in a pipeline, including turbulent flow and noise, and learn how you can reduce your risk with Fisher solutions.
See the difference valve trim can have on pipeline flow patterns in this side-by-side setup at the Emerson Innovation Center for Fisher technology.
Learn more about reducing flow pressure in stages to avoid the damaging effects of cavitation from sudden pressure drops.
使用 Fisher 控制阀和仪表可承受损坏性振动，从而降低维护成本。
